There’s a 3D-printed sundial that lets light through at the right angles to produce a digital clock shadow, which displays the...
There’s a 3D-printed sundial that lets light through at the right angles to produce a digital clock shadow, which displays the current time in 20-minute increments from 10:00 until 16:00.
Also, the necessary files can be downloaded from Thingiverse so you can 3D-print your own sundial, if you have the materials to do so.
